How big are they? Pointing up is male, pointing down both are most likely male as well. However, if you are keeping them at a temp of 80dF or lower, that will cause them to not fill out properly. What kind of diet are you feeding?
As far as breeding size, 2.75" +, but they only will get to be 3.5" SL. They need to be moved to a separate tank, as they require much higher temps than the other species you are keeping should be kept in.